Project 1. Diet and Exercise Modulate the Sperm Epigenome in Men It is well known that unhealthy diet and physical inactivity in young men and women are major contributors to later-life development of metabolic syndrome, diabetes and hyperlipidemia, leading to increased cardiovascular disease risk. Genome wide association studies have identified single nucleotide polymorphisms that can only explain about 20% of the heritability of these metabolic diseases. Preclinical models provide clear evidence that dietary or exercise modifications before conception result in metabolic and phenotypic changes in the offspring through intergenerational disruption of normal epigenetic regulations of gene expression. This occurs via alterations in i) DNA methylation, ii) histone modifications, and iii) non-coding RNAs (ncRNAs) both in animal studies and in men. Our central hypotheses are that overweight and inactive lifestyle results in epimutations in the sperm epigenome relative to the normal epigenetic programming in lean and active men and that diet and exercise modulation leads to reversal of these epimutations resulting in both a healthier ?phenotype? and ?epigenotype? which may persist after stopping the interventions. We propose three aims: Aim 1. Determines the differences in sperm epigenome (DNA methylation, histone modifications and non-coding RNAs) in a cross- sectional study in obese inactive vs. healthy active Hispanic men. We will recruit 20 healthy, active men and 80 obese and inactive Hispanic men between 18 and 40 years for this Aim. Only Hispanic men will be studied because of the high prevalence of obesity and inactivity in Hispanic younger men and to reduce the genetic variability influencing the epigenome. Aim 2. Characterize the plasticity of the sperm epigenome in response to 12-week diet and/or exercise training interventions in obese and inactive Hispanic men. 80 obese and inactive men will be randomized to 4 groups of 20 men: 1) No intervention (control); 2) Low fat, low caloric diet; 3) Supervised, periodized endurance and resistance training without modification of diet; and 4) Both exercise and diet modification. Sperm epimutations will be compared before and after intervention within each group and between groups. Aim 3. Identify the persistent effects of diet and exercise training at 12 and 36 weeks after cessation of interventions on the sperm epigenome after stopping the interventions. Project aligns seamlessly with the goals of the Center of Male Reproductive Epigenetics and with studies in mice in Project 2 and 3 that will reveal the mechanisms by which an unhealthy lifestyle leads to formation of epimutations in spermatozoa that are subsequently transmitted to, propagated within, and deleterious to male offspring ? based on mechanistic studies that cannot be done in men.